h1{
    text-align: center;
}

table{
    width: 90%;
    margin: 0 auto;
    border-collapse: collapse;
}

table,td,th{
    border: 1px solid #000000;
    text-align: center;
}

form{
    text-align: center;
    width: 90%;
    margin: 10px auto;
}

.empty-flight{
    height: 150px;
    vertical-align: center;
    text-align: center;
    font-size: 20px;
}

.grey,.ticket{
    background-color: #cccccc;
}